Methods and compositions for forming a specular coating film

Abstract

A method of making a specular reflective, mirror-like finish on a substrate comprising the steps of applying a one or more layers of a primer coating to the substrate and at least partially curing the primer coating; the following curing of the primer coating; applying an intermediate solution to the previously applied and cured primer coating, the intermediate solution comprising a vacuum metalized pigment in a solvent; further curing the primer coating and the intermediate coating to leave a substantially solvent-free intermediate coating; and applying, a transparent overlay coating to the cured intermediate coating.

1. A method of preparing a specular reflective coating on a substrate comprising:
 a) applying a one or more layers of a primer coating to the substrate and at least partially curing the primer coating, 
 b) following the at least partially curing of said primer coating, applying an intermediate solution to the previously applied and at least partially cured primer coating, the intermediate solution comprising a vacuum metalized pigment in a solvent, the intermediate solution being binder-free, 
 c) further curing the at least partially cured primer coating and the intermediate coating to leave a solvent-free intermediate coating, and 
 d) applying a transparent overlay coating to the cured intermediate coating. 
 
     
     
       2. The method of  claim 1  further including curing of the coated substrate after application of the transparent overlay coating. 
     
     
       3. The method of  claim 1  wherein the primer coating comprises a crosslinking binder, a solvent and pigments. 
     
     
       4. The method of  claim 3  wherein the crosslinking binder is a resin selected from the group consisting of:
 a) heat initiated cross-linking phenolic or melamine resins 
 b) cross-linkable isocyanate resins, and 
 c) epoxy resins, and water-soluble or water reducible versions of said resins. 
 
     
     
       5. The method of  claim 4  wherein the cross-linkable isocyanate resin is a polyurethane which may also include a metallic ion catalyst and the epoxy resins is crosslinkable by an amine or an amide group. 
     
     
       6. The method of  claim 3  wherein the pigment is black or grey in color. 
     
     
       7. The method of  claim 3  wherein the pigment comprises carbon black or carbon black blended with titanium white. 
     
     
       8. The method of  claim 3  wherein the primer coating further contains a wetting agent, a surfactant or a combination thereof. 
     
     
       9. The method of  claim 3  wherein the acceptability of the at least partially cured primer coating for application of the intermediate coating is determined by a solvent wipe test using a minimum of five wipes of methyl ethyl ketone. 
     
     
       10. The method of  claim 1  wherein the intermediate solution consists essentially of a vacuum metalized pigment in a solvent having a evaporation rate greater than about 4.0 and less than about 8.5. 
     
     
       11. The method of  claim 1  wherein the solvent in the intermediate solution comprises methyl ethyl ketone, acetone, methyl acetate, N-butyl alcohol, ethyl acetate or a combination thereof. 
     
     
       12. The method of  claim 1  wherein the transparent overlay coating comprises a clear polymeric resin. 
     
     
       13. The method of  claim 12  wherein the clear polymeric resin is a crosslinkable resin. 
     
     
       14. The method of  claim 12  wherein the clear polymeric resin is selected from the group consisting of crosslinkable acrylic polyols, polyester polyols, polyester resins, resins sprayable in powder form and UV curable resins and non-cross-linking solvent and water reducible acrylic resins, nitrocellulose lacquers and polyvinyl resins. 
     
     
       15. The method of  claim 12  wherein the transparent overlay coating additionally includes pigments or dyes. 
     
     
       16. The method of  claim 1  wherein:
 a) the primer coating comprises a two part mixture comprising, in a first part, an epoxy resin, a white pigment and a black epoxy paste, a surfactant and a solvent comprising a combination of methyl ethyl ketone, xylene and N-butyl alcohol, and, in a second part, an epoxy resin, an amine and a polyamide crosslinking agent, and a solvent comprising a combination of methyl ethyl ketone, xylene and N-butyl alcohol, 
 b) the intermediate solution comprises non-leafing metalized aluminum, acetone and ethyl acetate, and 
 c) the transparent overlay coating comprises an acrylic resin, a wetting agent, an isocyanate crosslinker, and a solvent comprising a combination of methyl ethyl ketone, ethyl acetate and N-butyl acetate. 
 
     
     
       17. The method of  claim 16  wherein the solvent in the primer coating is evaporated and the primer coating is cured for at least about 10 minutes at about 180° F., after application of the intermediate solution the solvent in the intermediate solution is evaporated and the primer coating and intermediate solution is cured for about at least an additional 20 minutes at about 200° F. and, after application of the overlay coating the overlay coating is cured for about at least an additional 15 minutes at about 200° F. 
     
     
       18. A method of preparing a specular reflective coating on a substrate comprising:
 a) applying a one or more layers of a primer coating to the substrate and at least partially curing the primer coating, 
 b) applying an intermediate solution to the previously applied primer coating, the intermediate solution comprising a vacuum metalized pigment in a solvent, the intermediate solution being binder-free and the vacuum metalized pigment being a non-leafing vacuum metalized aluminum; 
 c) further curing the at least partially cured primer coating and the intermediate coating to leave a solvent-free intermediate coating, and 
 d) applying a transparent overlay coating to the cured intermediate coating. 
 
     
     
       19. A method of preparing a specular reflective coating on a substrate comprising:
 a) applying a one or more layers of a primer coating to the substrate and at least partially curing the primer coating, said primer coating comprising a phenolic resin, a dispersant, a black pigment, a surfactant and a solvent comprising a combination of ethanol, methyl ethyl ketone, and N-butyl alcohol; 
 b) applying an intermediate solution to the previously applied primer coating, the intermediate solution comprising a non-leafing vacuum metalized aluminum pigment in a solvent, the intermediate solution being binder-free and comprising methyl ethyl ketone and N-butyl alcohol; 
 c) further curing the at least partially cured primer coating and the intermediate coating to leave a solvent-free intermediate coating, and 
 d) applying a transparent overlay coating to the cured intermediate coating, said transparent overlay coating comprising a polyurethane resin and an isocyanete cross-linker. 
 
     
     
       20. The method of  claim 19  wherein the solvent in the primer coating is evaporated and the primer coating is cured for at least about 20 minutes at about 250° F., after application of the intermediate solution the solvent in the intermediate solution is evaporated and the primer coating and intermediate solution is cured for about at least an additional 30 minutes at 300° F. and, after application of the overlay coating, the overlay coating is allowed to crosslink and cure. 
     
     
       21. The method of  claim 19  wherein the crosslinking and curing of the overlay coating is accelerated by heating for at least about 15 minutes at about 200° F. 
     
     
       22. A method of preparing a specular reflective coating on a substrate comprising:
 a) applying a one or more layers of a primer coating to the substrate and at least partially curing the primer coating, said primer coating comprising a two part mixture comprising, in a first part, an epoxy resin, a white pigment and a black epoxy paste, a surfactant and a solvent comprising a combination of methyl ethyl ketone, xylene and N-butyl alcohol, and, in a second part, an epoxy resin, an amine and a polyamide crosslinking agent, and a solvent comprising a combination of methyl ethyl ketone, xylene and N-butyl alcohol, 
 b) applying an intermediate solution to the previously applied primer coating, the intermediate solution comprising a non-leafing vacuum metalized aluminum pigment in a solvent, the intermediate solution being binder-free and comprising acetone and ethyl acetate; 
 c) further curing the at least partially cured primer coating and the intermediate coating to leave a solvent-free intermediate coating, and 
 d) applying a transparent overlay coating to the cured intermediate coating, said transparent overlay coating comprising an acrylic resin, a wetting agent, an isocyanate crosslinker, and a solvent comprising a combination of methyl ethyl ketone, ethyl acetate and N-butyl acetate. 
 
     
     
       23. The method of  claim 22  wherein the solvent in the primer coating is evaporated and the primer coating is cured for at least about 24 hours at about 70° F., after application of the intermediate solution the solvent in the intermediate solution is evaporated and the primer coating and intermediate solution is cured for about at least an additional 100 hours at about 70° F. and, after application of the overlay coating, the overlay coating is allowed to cure. 
     
     
       24. The method of  claim 22  wherein the solvent in the primer coating is evaporated and the primer coating is cured for at least about 10 minutes at about 180° F., after application of the intermediate solution the solvent in the intermediate solution is evaporated and the primer coating and intermediate solution is cured for about at least an additional 20 minutes at about 200° F. and, after application of the overlay coating, the overlay coating is cured for about at least an additional 15 minutes at about 200° F.